KINSHASA, Oct 19 (Reuters) - About 50 people were killed in southern Democratic Republic of Congo when a truck overturned and plunged into a river, the provincial governor"s office said on Tuesday. The accident occurred on Sunday in the copper-mining province of Haut Katanga, Governor Jacques Kyambula"s office said in a statement. Only two passengers in the truck survived, the statement said. Road accidents are common in Congo because of decrepit infrastructure and poor safety standards.